Bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) and ioxynil (3,5-diiodo-4-hydroxybenzonitrile) are well-known herbicides which are commonly used to control annual broadleaf weeds in wheat, barley, oats, rye, flax, and newly-seeded grasses. These materials are sold commercially as solutions of their octanoic acid esters in a suitable hydrocarbon oil in concentrations sufficient to provide 240 g/L of the active 2,6-dihalo-4-cyanophenoxy moiety present therein. However, even at such concentrations, crystallization of these solutions begins to occur at temperatures as high as 20.degree. F. (-7.degree. C.). At higher concentrations, crystallization occurs at even more elevated temperatures. For example, at concentrations of 480 g/L of the active 2,6-dihalo-4-cyanophenoxy moiety, crystallization takes place at about room temperature (20.degree. C.). Since these products are often shipped and marketed during the winter months, they frequently are rendered less effective, or even totally unusable, before they can be used unless precautions are taken to keep them above their crystallization temperatures.